Multi-point transmission is a concept wherein data is transmitted to a user equipment (UE) from geographically distributed transmission points (TPs), (e.g., base stations, eNodeBs, remote radio units (RRUs), etc.). Multi-point transmission schemes have been a part of the third generation (3G) specification for long-term evolution (LTE) networks since Release 11. They have been proven to be a powerful concept in achieving higher throughput and capacity, especially at the cell edge. However, the early versions of multi-point transmission schemes, especially those described in 3G Release 11, require ultra low latency transport support for fast coordination between the multiple-transmission points and a cloud based or centralized radio access network (C-RAN) architecture. With a C-RAN architecture, the baseband processing for many cells is centralized and a centralized scheduler is employed to coordinate transmissions between the TPs. These types of multi-point transmission schemes are referred to as “coordinated” multi-point (CoMP) transmission schemes.
5G wireless systems represent the next major phase of mobile telecommunications standards beyond. Rather than faster peak Internet connection speeds, 5G planning aims at higher capacity than 3G and fourth generation (4G) LTE systems, allowing higher number of mobile broadband users per area unit, and allowing consumption of higher or unlimited data quantities. This would make it feasible for a large portion of the population to stream high-definition media many hours per day with their mobile devices, when out of reach of wireless fidelity hotspots.
Multi-point transmission has become an essential technique to improve the fairness and reliability of a wireless network. Multi-point transmission will be particularly important in future wireless networks such as 5G networks and beyond, since operating at high frequency makes cell edge guarantee a very difficult proposition. However, the low latency transport and C-RAN architecture requirements of CoMP transmission schemes are becoming progressively more difficult to achieve in advanced wireless communication systems, such as advanced LTE systems, 5G systems, and beyond. This is because advanced wireless networks require super low latency and high bandwidth. For example, in 5G networks, the time-scales over which TP schedulers need to be coordinated can be significantly less than the times-scales in LTE, due to a smaller transmission time interval (TTI) used to achieve super low latency (e.g., from about 125 micro seconds (μsec) to about 250 μsec for 5G compared to 1.0 millisecond (msec) for LTE). With such a tight scheduling time-scale for coordination, it is difficult to realize a C-RAN architecture for 5G under certain scenarios. Accordingly, multi-point transmission schemes that do not require the tight scheduling coordination between TPs associated with current CoMP transmission schemes are needed for advanced wireless networks.